Lab tests vs. the real world

Thursday, 3 March 2011

Several people have been returning to a piece from this time last year when I revealed Quick Step thought about signing Peter Sagan but eventually decided against it and the Slovak wunderkind joined Liquigas. What’s the Dutch word for regret?

QS team manager Lefevere said Sagan delivered good results in an effort test and a reader saw this and got in touch to ask what these tests are all about. So here’s some more info on the tests, what they involve and what they mean.

The protocol
For cyclists the tests are conducted on a static bike. VO2 Max is short for the maximum (max) volume (V) of oxygen (02) someone can carry when exercising. More formally it’s the “maximum capacity of an individual’s body to transport and use oxygen during incremental exercise”.

Once a rider is clipped into the bike and hooked up to measuring devices the test starts with a good warm up and then the rider starts at a set effort. At set intervals the effort is increased, for example the resistance on the bike is increased. Gradually it gets harder and harder and eventually there comes the point where the rider is forced to sprint just to keep going and then exhaustion sets in and the rider stops. A rider can only sustain 100% VO2 Max for a short while, usually a few minutes.

It’s not to be confused with maximum power, a peak number you can might in a sprint. Nor is the VO2 Max reached at maximum heart rate. Instead it’s obtained during the test and marks a point when the body can’t carry any more oxygen, even if you can temporarily up the effort. It’s where your ability to carry oxygen reaches a plateau.

After the test the data are gathered and the rider’s score can be determined. The ability to transport oxygen is obviously crucial in an aerobic sport like cycling. It explains why blood manipulating and doping have such a hold on the sport but that’s for another day. As such a rider’s score in the lab correlates to their performance on the road. The higher the score, the better the racer. Indeed it can get quite reductionist, especially if you want to compare mountain climbing abilities as given the VO2 Max data, the wattages, a rider’s weight and not much more you should see lab results translate quite directly into abilities.

Weak numbers. Really?

In the real world
But it’s not always so predictable. When the T-Mobile squad gathered at the start of 2007 one of the first tasks was an effort test to measure the fitness of all the riders. Having tested all the riders, one stood out thanks to relatively poor results, a neo-pro called Mark Cavendish. The trainer had words with the young rider, saying he doubted whether the rider was good enough for the Pro Tour. Certainly the lab test doesn’t account for aerodynamics, a low position on the bike means less watts. Indeed today Cavendish puts out fewer watts than team mates Renshaw and Eisel, by a substantial margin yet he is probably the fastest rider going.

But it’s not so simple as saying people who score bad numbers can become champions. When Cavendish took the test he was not in great shape. Commenting on the beginning of Cavendish’s time with T-Mobile, former team mate Roger Hammond said “he started the season so catastrophically that the staff were wondering what they could enter Mark for so that he could finish the race“.

That said Cavendish is not alone in producing relatively uninspiring numbers yet delivering results. Johan Museeuw was a prolific classics winner in the 1990s yet didn’t impress on the static bike either. And there are others too

Scores
Expressed as ml/kg/minute, a measure that accounts for body size to allow comparisons, the numbers can vary. The “man in the street” might score 40ml/kg/min, a frequent cyclist 50-60ml/kg/min and a pro normally gets 70ml/kg/min with the best hitting 80ml/kg/min.

Note you can’t always compare numbers across sports since different muscle groups are used. Even in cycling the numbers can vary according to the lab accuracy and height above sea level has a significant effect too.

Raw data
As ever the VO2 max test is only one tool to measure talent. Take just one measurement and you’ll never get the full picture. Sagan was invited to do some tests after impressive results on the road, the lab just confirmed what he’d got at that moment in time, they probably didn’t alert Quick Step to Sagan’s potential.

Nobody wins trophies, jerseys and medals for high scores in the lab. But the effort test is a common part of the “interview” process for a team looking to recruit a new rider and an ongoing way to measure a rider throughout the year.

I’ve heard that power profiles are being introduced in addition to Haemocrit levels to create a more decisive Biological passpsort.

From my limited knowledge; VO2max is a function of lung capacity, but I assume it can also be altered by varying Haemocrit levels, as the blood that passes through the lungs can take more oxygen on board, if this is the case surely it can be used in addition to the former pair of values?

Naturally an athelete’s VO2max should not step change, therefore it is an inherently useful parameter to detect “le dopage”.

An individuals VO2max is defiantly not related to lung volume. The blood that passes through the lungs is easily saturated with oxygen even if the alveoli surface area is not optimal. Interestingly peak 5min power is a good predictor of VO2 max. This equation is usually about 95% accurate at predicting VO2 max. VO2(L/min) = peak power x 0.01141 + 0.435. Multiply this number by 1000 and divide it by your body mass (kg) and you get a good representation of your VO2max.

I also feel different when doing a VO2 max test. When i just had one done my max heart rate was considerably lower than when on the road. I agree with Inner Ring in when he said that these tests are not a good indicator because smaller riders don’t have to produce the wattages of the bigger riders.

Cam Austin: that’s true but like all profiling, I suspect it can be fooled. A rider only has to fake in the test, to soft-pedal and the data are manipulated. But a career of logged tests is something that a careful team would use. Like all data, it helps but can’t be seen in isolation; I suspect you know this.

Stephen lane: thanks, I’ll give that a go.

Qwerty / Houston / Starr: yes, it’s one thing in the lab but another on the road. Thankfully so.

Stephen Lane: I think that calculation must be for men only? Because I get a whopping score of 74 when I put in my numbers (known, proven 5-min peak power) and as a 30-something high level amateur woman that’s astronomical! (all the pro teams should be calling me up… not).

Joe Friel had a theory as to why power output was lower on a trainer inside than on the road. His theory was that the micro-periods of rest on the road can result in just enough rest for recovery that power output is actually increased over 20 – 40 – 60 minute periods of time.

As for Cavendish, he may have lower overall power numbers, but if you think of it, he is on odd duck. He essentially rides at tempo every race until the final bunch sprint, and then has a leadout which further protects him from having to go all out. He essentially a track rider who is dragged along until the bitter end. No offense to Cav, but this could be why he has not been able to translate his sprint success into a more complete rider who can compete in the Classics.

if there is such a diffrence between lab tests and reality. why was there a story saying lap tests could be part of bio passport data. espessialy as motivation is a factor, accurate/reliable results will be to find.

Cav and his bad numbers is either not true, just used to create publicity, or shameless acknowledgment of the quality of his Program.

Sure, an ordinary rider may survive 6-7 hours on the bike better than someone with great numbers. But BAD numbers, you’re just off the back, early. And remember, sprinting on the road isn’t max power match sprinting on the track. It’s a 3-5 minute VO2 effort followed by a 30 second all out effort. More of an aerobic effort than max power, even without considering the previous 6 hours on the bike.

The more I hear about Cav’s bad numbers and aerodynamics the more I think about “high cadence, increased efficiency on the bike, unprecedented technological advancements, and out working those lazy Europeans”

If Cavendish benefits from “aerodynamic arbitrage” as much as people speculate that he does, then I would expect to start seeing the sprinters follow the TT specialists into the wind tunnel, and eventually that advantage might go away. It also raises an interesting question: were there any top sprinters of the past who may have benefited from an unusually aerodynamic position on the bike compared to their competitors?

Anon: yes, even labs can vary and the strain gauges are more precise than the everyday power measurements.

Matt: indeed. I think it can help but if people are going as far as to store blood, maybe they’ll try to “game” a lab test too? Although you can tell if they’re slacking by looking at heart rate, no?

Q, ColoradoGoat & jza: it’s still relative. We’ve seen how he gets over the Poggio after 295km. He’s got over the mountains in the Tour de France within the delays. Don’t forget Stage 19 of the 2009 Tour when he made it over a Cat 2 climb 16km from the finish whilst the race was at full speed. Yes, there are less watts than others but it’s not just about being low. He’s got good leg speed and posture for sprinting.

Exactly IR, so is he a diamond in the rough, or a freak responder to ‘modern training methods’?

Mark, I was thinking of another rider who credited a bunch of obscure and inconsequential training methods for his transformation from above-average-rider to so-fast-nobody-can-ever-even-hope-to-get-anywhere-close. Song remains the same.

Maryka: The formula should work for both males and females. Id say what is probably out is the 5min power. I suggested 5min power, but it is actually the peak power reached during an incremental test like a VO2max test. It is supposed to represent your power output at VO2max. In such an incremental test the final power stage in which you fatigue is preceded by 10-15 minutes of gradually increasing intensity so you are ‘pre-fatigued’ before this point. A straight 5min power from WKO or training peaks may over estimate the number slightly. 74mL/kg would be nice though!!